Boil Release (沸遁, Futton; Viz "Vapour Style") is an advanced naturekekkei genkai made up of techniques that combine fire and water-based chakra to create gaseous materials in different properties and usages.
Mei Terumī utilises powerful corrosive vapour capable of dissolving anything. She is also able to control the range and level of the vapour's acidity. Not only is it dangerous to be near, but as being gaseous, it can cover a considerable range shortly, and go through small spaces. It also stays in the air, so it can potentially deal continuous damage if the enemy is trapped or knocked back into its range. The only example of this version of Boil Release, Skilled Mist Technique, demonstrates that this kekkei genkai is strong enough to dissolve Susanoo's ribs; an impressive feat, as Sasuke has stated that Susanoo is even more of an absolute defence than Gaara's Shield of Sand. It however has the inherent flaw of being able to harm allies, so it is critical to control the level and range of the attack, and use it in a smart area.
Kokuō and its jinchūriki utilises steam, by increasing the temperature of chakra to boiling point (沸点, futten). In this version, steam is released, and can be either used as a form of propulsion, increasing the power and speed of a taijutsu technique, or can be spread instantly from their body to burn or melt their surroundings due its high temperature.